Electric circuit controller



Jan. 14, 1947.

H. R. JOHNSON ELECTRIC CIRCUIT CONTROLLER Filed July 11, 1944 3 Sheets-Sheet 1 jfcTi-T. IE1. E

awe/wick I; & Sammy Jan. 14, 1947.

H. R. JOHNSON 'ELECTRIG CIRCUIT CONTROLLER Filed July 11, 1944 3 Sheets-Sheet 2 iii-.1 U

Jan. 14, 1947. 1-1. R. JOHNSON ELECTRIC CIRCUIT CONTROLLER 3 Sheets-Sheet 3 Filed July ll, 1944 Patented Jan. 14, 1947 UNITED STATES Lei git? PATENT OFFICE 7 Claims.

My invention relates broadly to electric circuit controllers and more particularly to electric circuit controllers of the multiple push key type.

One of the objects of my invention is to provide an improvedconstructicn of multiple push key assembly for the control of electrical circuits where errors in circuit selection due to the simultaneous operation of more than one push key of the assembly are prevented.

Another object of my invention is to provide a construction of cam abutment for a multiplicity of push keys for effectively blocking the simultaneous operation of more than one key selector in a multiple key assembly.

Still another object of my invention is to provide a construction of automatically adjustable abutment for coaction with the several push keys of a multiple push key assembly for obstructing the simultaneous operation of two push keys of a multiple push key assembly.

Still another object of my invention i to provide a construction of automatically adjustable abutment which may be readily added to existing multiple push key actuated switches for locking the push key switches against accidental simultaneous operation of two adjacent keys.

Other and further objects of my'invention reside in the improved operation of multiple push key assemblies including an arrangement of safety lock for insuring individual operation of the push key switches of a push key assembly as set forth more fullyiin the specification hereinafter following by reference to'the' accompanying drawings in which:

Figure 1 is a plan view of the electric circuit controller of my invention illustrating a multiple key assembly embodying the safety locking device of my invention; Fig. 2 is a transverse sectional view taken on line 22 of Fig. 1 illustrating the interlocking mechanism associated with the push key assembly for eifecting release of one key upon operation of another key of the coacting assembly; Fig. 3 is a longitudinal sectional view through one of the push keys of the push key assembly of my invention and illustrating the closed circuit condition of the electrical pile-up assemblies preceding the operation of the push key; Fig. 4 illustrates the position of the parts upon operation of the push key illustrated in Fig. 3 showing the make before break condition of the electrical control circuit through the spring pile-up assembliesafter actuation of the push key; Fig. 5 is a process of being'moved into position for establishing electrical contact with circuit terminus in .the associated push key cabinet, the structure being illustrated in section to illustrate the restrictive means which I provide for preventing accidental operation of more than one push key selector at the same time; Fig. 6 is a transverse sectional view taken on line 66 of Fig. 5 and illustrating the flat cams which I provide for preventing simultaneous operation of more than one selector of the push key assembly; Fig. 7 is a cross sectional view taken on line 'I! of Fig. 6 and illustrating one of the cam members slideable in the slot in the support of the push key assembly and the means for retaining such cam members in position for longitudinal movement; Fig 8 is a. longitudinal sectional view taken through the support carried by the push key assembly and showing the longitudinally extending slot therein within which the multiplicity of cams operate; Fig. 9 is a perspective view of one of the trapezoidal shaped fiat sheet-like cams employed in the push key assembly of my invention; Fig. 10 is a schematic view illustrating the manner of operating one of the selectors of the push key assembly and the mutual coaction of the cam members with the other selectors of the push key assembly for obstructing operation thereof; Fig. 11 is a schematic view similar to the view illustrated in Fig. 10 but illustrating the manner in which an adjacent selector is blocked upon operation of one of the selectors for preventing accidental simultaneous operation of more than one selector at the same time; Fig. 12 is a schematic wiring diagram of two electric circuit controllers embodying my invention associated with two line circuits and with a printing telegraph equipment and illustrating the importancev of the provision of means, in accordance with my invention for preventing simultaneous interconnection of two line circuits through switching keys to the same equipment for thereby subjecting the equipment to excessive currents from the two line circuits, the View showing the adverse condition arising in the event that two circuit controllers should be depressedv at the same time; and Fig. 13 is a schematic view showing the desired operation of the circuit system under control of electric circuit controllers in accordance with my invention where the restrictive stop means provided by my invention preclude connection of two line circuits to the equipment thereby carrying out the protection afforded by the structure of my invention.

My invention is directedto a construction of safety locking device for push keys used in the control of electric circuits. Push key switches are generally assembled in a strip, which in the application of my invention illustrated herein comprises a multiplicity of six push keys. While I have illustrated my invention applied to an assembly of six push keys, it is to be understood that my invention is equally applicable to assemblies of larger numbers of push keys, such as twenty keys to the strip assembly. The push key strips which I have selected for purposes of illustrating my invention are generally employed in the switching of automatic printing telegraph equipment from one line circuit to another where it is extremely important that no open circuit.

should exist during the switching interval. The push key strip assembly comprises a multiplicity of spring pile-up assemblies of the make before break type with respect to which the individual push keys operate. An interlocking mechanism is provided which coacts with all of the push keys of the push key assembly which provides for the operation of a selected key of the key assembly which when operated releases a coacting key of the key assembly. Thus it is possible to connect automatic printing telegraph apparatus to a line circuit before disconnecting other printing telegraph apparatus from that line circuit. I have found, however, that the interlocking mechanism is insufiicient to prevent detrimental conditions arising Where two or more selectors may be pushed simultaneously thereby placing one automatic printing telegraph equipment on more than one line circuit. The interlocking mechanism has not proven satisfactory for several reasons:

(a) If an operator is not overly cautious or if he so desires, hemay press down two or more selectors simultaneously. This will cause very unsatisfactory operating conditions due to one piece of equipment being connected to more than one line circuit, at the same time resulting in damage to equipment due to excessive current and also garbling. or unreadable printing on the circuits involved.

(12) If a previously operated key should momentarily stick while making a circuit selection by pressing another selector, then there will be two or more circuits connected to the same piece of equipment; the final result of such operation will be the same as described in paragraph (a) above.

The selectors in a push key assembly are operated by finger actuated push buttons and under the stress of operating conditions it is not unusual for an operator to unintentionally strike the buttons of two adjacent selectors and accidentally push both selectors into operating position simultaneously. As pointed out the increase in current upon the equipment connected through the associated electrical contacts to the associated electrical circuits may damage the equipment. The relay windings or the operating solenoids of such equipment may be subjected under these conditions to detrimental excessive currents.

The improvements provided by the structure of my invention may be added to existing constructions of push keys for preventing the simultaneous operation of two or more selectors by arranging a, multiplicity of adjustable cams in the path of movement of the selectors. These cams are arranged to automatically and mutually coact to provide a restrictive abutment against the. operation of more than one selector of thetured at the front as represented at 2 and provided with guide rails designated at 3 for receiving the removable key strip assembly designated generally at 4. The key strip assembly 4 is represented in this particular disclosure as embodying six push keys represented at 5, 6, l, 8, 9 and Ill operative from the front of the push key cabinet structure. It will be understood that my invention is equally applicable to a push key assembly embodying various numbers of coacting push keys such as ten or twenty. The push key assembly includes a frame formed by posts H and i2 secured by tie bolts 14 and i5 to the strip member IS. The tie bolts I4 and I5 pass through spacer members I! and I8 and through the ends of support I 9 and enter the ends of posts II and i2. At one end of the frame tie bolt 54 passes through spacer washer 20 while at the other end of the frame tie bolt l5 passes through the end of spring member 2|. Spring member 2! bears against interlock strip 22 tending to force interlock strip 22 in a position for latching any one of the push keys which may be depressed and effecting a release of any one of the push keys which may have been previously depressed. The interlock strip 22 is slotted at opposite ends as represented at 23 and 24 to slideably engage in annular grooves 25 and 26 formed in spacer members I? and 18. The interlock strip 22 is provided with apertures shown at 21, 28, 29, 39, 3| and 32 which are spaced in alignment with the interlock cams carried by the stem members of each of the push keys. I have shown the interlock members at 33, 34, 35, 35, 37 and 38 carried by the stem members 39, 40, 4|, 42, 43 and 44 of each of the push keys 5, 6, l, 8, 9 and II] respectively. The interlock cams are shaped in cooperation with the aligned apertures in the interlock strip 22 so that the cam surface of interlock cams operate to efiect a displacement of the interlock strip under which the interlock cams engage as the push keys are depressed. The mode of operation is illustrated in Figs. 10 and 11 in which push key 1 is shown depressed and wherein interlock cam 35 has passed through aperture 29 in interlock strip 22 and has become interlocked with respect thereto thus retaining a depressed key in actuated position subject to release when another push key of the push key assembly is depressed. The efiect of depressing another push key of the push key assembly is to move the interlock cam carried by the stem of that selected key against the aligned aperture in the interlock strip 22 which shifts the interlock strip 22 to a position allowing return of the previously depressed push key by enabling the associated coil spring of the previously selected push key to return the interlock cam thereof through the associated aperture in the interlock strip-22. It will be understood that selection of a second key has the effect of displacing the interlock strip 22 to a position in which it is no longer effective as a lock to retain a previously selected key inasmuch as the aperture in the interlock strip 22 becomes so concentrically aligned with the interlock cam on the said push key stem that the push key stem is forced outwardly under pressure from the associated coil spring for thus restoring the previously selected push key to normal position. The coil springs which effect the I restoring of each of the push keys are represented at 45, 45, 41, 48, 49 and 5B. These coil springs are concentrically disposed on the respective stem members 39, 40, 4!, 42, 43 and 44 intermediate the spring pile-up assembly actuating cams and the cam retaining strip member 5| carried by support; .I 9. Thecamxretaining strip member is aperturedat spaced 'Jintervals along the length.

thereoftfor receiving the variably :movable ends of the :stems139; 403,41, 42, 43 and 44. The coil springs.:45, 46,.41, 4B, 49*and 56 bearing against the cam retainingstrip member 5! and effective against the spring pile-up assembly actuating cams. tendtocontinuously urge the push keys into restored'po'sition and resist the depressed position thereof. The spring pile-..up;assembly actuating camscarried bythe'trespect'ive stem members are each fOIIll'GdJfI'OIIl' insulation material and are spring-'pile-up assembly actuating cam as shown at 54 in Figs. 3 'an'dz4. The normal position of the push keyis illustrated in Fig. 7 in which the circuit between contact strip 63 and contact strip 54 is closed and the-circuit between actuating spring BI and contact strip 65 is open. Likewise the circuit between contact strip 66 and contact strip 64 is normally closed while the circuit between actuating spring 62 and contact strip 64 is open.

Under the depressed condition of push key 1 the spring pile-up assembly actuating cam 55 serves to spread actuating springs BI and 62 first making connection between the spring strips 65 and 65 and strips 52 and 64 and then breaking connection between strips 63 and 65 and 65 and 62. Thus circuit continuity is always maintained as a make before break is established. I

The improved construction of my invention will be understood by reference to Figs. 5-11 in which it will be seen that the support [9 is provided with a longitudinally extending milled slot 10. This milled slot is actually in width which is substantially less than the diameter of the recesses into which the ends of the stem members 39, 40, 4|, 42, 43 and 44 of the push keys are arranged to variably'extend. The slot, however; will receive for slidable movement the cam members which are ee in thickness. These recesses which are drilled into the support !9 are shown at H, l2, l3, l4, l5 and 16. In Fig. 8 these recesses appear as only partial cylindrical sections of'the circular recesses on either side of the longitudinally extending slot H3. These recesses serve as guides for the ends of the respective stems of the push keys which are variably projected and retracted through the aligned apertures in the cam retaining strip 5!. The housing formed by the milled slot 10 and the cam retaining strip 5! serves as an enclosure for sets of slidable cam members mounted end to end as represented at i1, l8, 19, 80 andBl. The cam members are each polygonal or trapezoidal in shape and are free to be displaced endwise in the path of'the var ably projecting stem membars. The relationship'of the total length of the milled slot 10 to the length of the individual cams H, 1'8, 19, 8i! and 8| slidable end toend is such that on stemt'membermaybe-depressed 6. the: cams to: an extreme limiting position com.- pletely filling the slot 10 end to end. That is, the. polygonal. or trapezoidal. cams are mutually slidable. end to end and coact to displace each other when pressure is impressed on any one cam member or upon any two adjacent cam members. When the trapezoidal or polygonal cams have been shifted longitudinally due to a transverse pressurev being impressed upon any one or two adjacent cam'members by the projection of a stem membenthe several cams occupy such a position that no associated selector in the push key assembly can be operated until the previously selected push key has been released. Moreover, the operation of the cam members is in the nature of a chain in which one slidable cam member displaces its neighboring or adjacent cam member so that should two push keys be accidentally pushed simultaneously as represented, for example, in Fig. 11 it will be impos sible to function either one of the adjacent push keys due to the mutual blocking action which is brought about by the adjacent coacting cams. The-blocking action by the coacting cams is brought into'opera'tion prior to the functioning of the interlock strip 22. Therefore, the pushing of two keys simultaneously merely has the effect of mutually reventing operation of any of the keys. The simultaneously operated push keys are then'immediately restored under action of the associated coil springs and without functioning the associated contacts in the spring pile up assemblies; Referring to Fig. 3, the only result produced upon the accidental depression of two keys :2. simultaneously is that the cylindrical portion of the insulated cam 54 rides horizontally upon the'inwardly directed spring members SI and B2 producing no displacement of the contacts of the springpile up assemblies at all. It is only when one of the push" keys of the push key assembly is functioned alone, as represented in Fig. 10, that the restriction upon the movement of the associated push keys is removed, allowing one push key to be-moved to suflicient distance to permit the interlock to function.

The key strip unit has the front strip 16 thereof finished with an escutcheon plate which I have designated at 82. The interior of the strip 56 is lined with a silencing strip shown at 83 to'substantially dead'en or eliminate any sound due to rebound of-the interlocking cams 33, 34, 35, 36, 3'! and 38.

The leaf springs of the spring pile up assemblies are connected to spring socket members whichI have indicated at 84' and 85 mounted on an insulated panel structure 86 which is supported by transverse strip 31 which extends between the guides 88 and 89 which are grooved to enga e the guide rails 3 in the cabinet structure I. The cabinet structure includes panel facilities having pin terminals thereon which are adapted to be engaged by the sockets represented at 34'and 85'for establishing detachable connection between the removable key strip assembly andthe circuits of the cabinet structure. The sockets 84* and 85 are connected through suitable busses represented generally at 9!! extending between lugs' 9! of the socket terminals'and the lugs '92 of the spring pile up assemblies.

The importanceofthe system of blocking the simultaneous operation of more than one push key will be understood more completely by referenceto the schematic diagrams of Figs. 12 and.

13. 1 .1 have designated at $4 anequipment such as a printing telegraph apparatus which it is desired to switch from one line'circuit-to another line circuit. Each line circuit is supplied with line current facilities. I have designated the two line circuits at 95 and 96. In order to fully appreciate the conditions existing in these line circuits I have designated line circuit 95 as including line current #1 and line circuit 96 as including line current #2. Any condition which would permit line current #1 to be added to line current #2 and impressed upon equipment 94 might be highly detrimental to the operation of equipment 94 and might in fact subject such equipment to damage. Such conditions have heretofore been encountered-in practice where two push keys of the switching apparatus locked in actuated position at the same time; A sticking key which was not released upon the operation of a previously selected key produces the same damage and detrimental results as an accidentally simultaneously operated key. There-' fore, the importance of my improvement becomes apparent when it is realized that it is impossible to subject the equipment 94 to the sum of the two line currents. In Fig. 12 I have shown push key I and adjacent push key 8 both actuated by an accidental condition or a condition in which mechanism as previously available in the art has failed to release a previously actuated push key upon the operation of a second push key. Under this condition it will be seen, as illustrated in 12, that the spring pile up assemblies 58 and 69 and 58' and 69' have become parallel as a result of which line current #1 from line circuit 95 passes through contacts 65 and 64 and leaf springs iii and 62 to the equipment 94 while line current #2 from line circuit 96 passes through contacts 65' and 64 and leaf springs BI and 52 to the same equipment 94, subjecting the equipment 94 to the integral or current #1 and current #2 to the detriment and injury of the equipment 94.

On the contrary in the system of my invention as depicted in Fig. 13, push key 1 when actuated to place line current #1 on line circuit 95 through contact 65 and leaf spring BI and contact 64 and leaf spring 62 on equipment 94 completes the circuit to equipment 94 without any possibility of line current 2 from line circuit 95 entering equipment 94 through contact 65' and open circuit contact strip 6| or contact 64' and open circuit contact 62'. Push key 8 is prevented from operating the spring pile up assemblies 58' and 69', first by the blocking action of cam 89 which interferes with and restricts the movement of stem member 42, and second by the operation of the inte lock strip 22 with respect to cam 39.

In. the drawings I have shown the ends of the push key stems and the opposite ends of the bases of the trapezoidal cams formed abruptly at a sharp angle for the purpose of more clearly illustrating the principle of operation of the key system. It will be understood that in carrying out my invention in practice the extremities of the push key stem may be rounded and the bases of the trapezoidal-shaped cam members may terminate in filletsol' rounded corners to eliminate any possibility of sticking of the push key stems and to reduce frictional resistance in the longitudinal displacement of the series of cams. To further reduce frictional resistance in the movement of the cams, I may introduce lubricating grease or oil into the slot 10. To eliminate wearing'of the support l9 and the cam members 11,

18, 19, 80 and BI, I may form these parts fro hardened or heat treated material.

its preferred embodiments but I realize that modifications may be made in details of construction and I desire that my disclosure herein be con-I sidered in the illustrative sense rather than the limiting sense and I intend no limitations upon. my invention other than may be imposed by the.

scope of the appended claims.

What I claim and desire to secure by Letters Patent of the United States is as follows:

1. An electric circuit controller comprising a frame assembly including a multiplicity of depressible keys, spring pile-up assemblies associated with each of said depressible keys, stem members extending from said depressible keys, a support for said spring pile-up assemblies, said support having spaced substantially cylindrical recesses therein to permit the entry of said stem members, a slot extending through said support and through the substantially cylindrical recesses therein and a multiplicity of coacting cams slideably mounted end to end in the slot in said support and substantially aligned with the recesses into which said stems project and subject to mutual displacement with respect to the projecting ends of said stems for mutually blocking the simultaneous movement of more than one of said stem members.

2. An electric circuit controller comprising a frame assembly including a multiplicity of depressible keys, spring pile-up assemblies associated with each of said depressible keys, stem members extending from said depressible keys, a support for said spring pile-up assemblies, said support having a plurality of spaced longitudinally extending recesses axially aligned with said stem members for slideably receiving and guiding the ends of said stem members, a slot extending through said support and through the recesses therein and means carried by said support and displaceable through said slot for mutually blocking the simultaneous movement of more than one of said stem members in said longitudinally extending recesses.

3. An electric circuit controller comprising a;

frame assembly including a multiplicity of de: pressible keys, spring pile-up assemblies associated with each of said depressible keys, stem members extending from said depressible keys, a

support for said spring pile-up assemblies, said support having guide-ways therein for slideably embracing the ends of said stem members, a slot extending through said support and through the guide-ways therein and a multiplicity of mutually displaceable means disposed in the slot through support for said spring pile-up assemblies, said. support having spaced socket-like recesses there-.' in, a slot extending through said support and through the socket-like recesses therein and a multiplicity of trapezoidal members mounted end to end and slideable in the slot in said support and mutually coacting with the ends of said stem members for blocking the simultaneous movement of more than one of said stem members through said socket-like recesses, said socketlike recesses having a depth sufficient to maintain alignment of said stem members in either the depressed or restored positions thereof.

5. An electric circuit controller comprising a frame assembly including a multiplicity of depressible keys operative to either an actuated or 2, released position, spring pile-up assemblies associated with each of said depressible keys, stem members extending from said depressible keys, a support for said spring pile-up assemblies, said support having a multiplicity of axially extending socket recesses therein for receiving and guiding the ends of the stem members, a slot extending through said support and through the recesses therein and a multiplicity of polygonal shaped members slideably mounted end to end in the slot in said support and mutually coacting with the ends of said stem members for blocking the simultaneous movement of more than one of said stem members through said socket recesses.

6. An electric circuit controller comprising a frame assembly including a multiplicity of depressible keys, spring pile-up assemblies associated with each of said depressible keys, stem members extending from said depressible keys, a support for said spring pile-up assemblies, said support having a stabilizing and guiding socket therein individual to each of said stem members for maintaining said stem members in spaced alignment in either the actuated or released positions thereof, a slot extending through said support and through the recesses therein and a plurality of flat sheet-like members slideably mounted end to end in the slot in said support with their adjacent ends shaped to coact with the projecting ends of said stem members for mutually restricting the simultaneous movement of more than one of said stem members through said stabilizing and guiding sockets.

7. An electric circuit controller comprising a frame assembly including a multiplicity of depressible keys, spring pile-up assemblies associated with each of said depressible keys, stem members extending from said depressible keys, a support for said spring pile-up assemblies, said support including a multiplicity of spaced sleevelike recesses therein substantially coniorming in section with the section of said stems and aligned with said stems for guiding said stems in both depressed and restored positions, a. slot extending through said support and through the recesses therein and a plurality of fiat sheet-like members slideably mounted end to end in the slot in said support with their adjacent ends constituted by cam faces coacting With the projecting ends of said stem members and subject to mutual displacement with respect to the projecting ends of said stem members for mutually obstructing the simultaneous movement of more than one of said stem members.

HENRY R. JOHNSON. 

